Der gemeine Ami ist eine faule Socke und wenn er was abkürzen kann, dann tut er’s. Und so wird der “Quacksalber” zum “quack”.
Etymology: The word “quack” derives from the archaic word “quacksalver,” of Dutch origin (spelled kwakzalver in contemporary Dutch), meaning “a boaster who applies a salve.” In the Middle Ages the word quack meant “shouting”. The quacksalvers sold their wares on the market shouting in a loud voice; synonyms: charlatan, con artist, fraud, imposter, mountebank